Put in Browser : opera://settings/?search=flash
For your readers who are not as technically savvy as you, would you be a bit more clear? E.g., you said: Put in Browser : opera://settings/?search=flash.

My experience was the same as yours running the same version of Opera. What I did was to change the settings for cookies to <Keep local data only until I quit my browser>, quit & relaunched Opera and the cookies were gone.

When I go to a newspaper article and click on Opera's share icon, then mouse down to Mail, it opens a new email in Apple's Mail.app with only the URL of the article.
When I do the same thing in Safari, it opens a new email in Apple's Mail.app with the entire text of the article including photos.
That would be a wonderful feature to have because: when you send full articles, there is no danger that the person to whom you are sending them will eventually reach the limit of X free articles per month posed by some sites with a paywall.
Otherwise, just loving Opera and have made it my default browser.